The logistic distribution is a continous probability distribution. It
has two parameters - location and scale. The cumulative distribution
function of the logistic distribution appears in logistic regression
and feedforward neural networks. Among other applications, United State
Chess Federation and FIDE use it to calculate chess ratings.

The following graph shows how the distribution changes as the parameters
change:

The logistic distribution is implemented in terms of the std::exp and the std::log
functions, so its accuracy is related to the accurate implementations
of those functions on a given platform. When calculating the quantile
with a non-zero position parameter catastrophic
cancellation errors can occur: in such cases, only a low absolute
error can be guarenteed.